308 DESCRIPTION OF CHALK CORALS. 
Four of the specimens exhibited portions of a root, or the part of the coral 
immediately adjacent to that structure (figs. 3,5). The root itself was composed 
of the small tubuli, and the best example (fig. 5*) presented a short thickish stem 
with a slight but fractured expansion at the base, the under side of which had 
been moulded upon a rough convex surface. From this base the branches in all 
cases diverged almost horizontally or at an approximation to a right angle ; but 
the development was apparently unequal, as if the root had been attached to a 
more or less vertical surface, and the coral had grown upwards, and to a certain 
degree laterally but very slightly in an opposite, which would have been a down- 
ward, direction. ‘This supposition, if correct, would account for the apparently 
horizontal position of the branches, and allow of a cyathiform mode of growth, 
if a base had been attached to a suitable surface. The mode of branching was 
essentially lateral, no direct bifurcation having been noticed, but the develop- 
ment of shoots was very unequal, depending clearly on the amount of interspace, 
and being entirely wanting where two parallel branches were in close proximity. 
Where most regularly produced, the pinne issued alternately on opposite sides, 
and when space permitted them to assume the character of secondary branches, 
they gave off in their turn other pinne, the only limit to ramification depending on 
the intervals. So far as was observed they sprang froin near the back (figs.3b,4d), 
and consisted almost wholly of large tubes. On some few occasions branches 
touched, but without perfectly anastomosing, the points of contact being generally 
the extremity of one branch and the side of another. The surface characters of the 
tubes, particularly of the larger series, was seldom well exhibited. In the best 
preserved cases it presented a semicylindrical, thin lamina of variable extent, 
projecting more or less boldly, and covering the furrow which extended upwards 
from the usually preserved aperture, the true mouth being a simple tubular ex- 
tremity. The characters of the small tubuli were often well shown on the sides 
of the branches (fig. 3 6), and exhibited, as before stated, no essential deviations 
except in size from the visceral tubes. The general characters of the interior of 
the coral may be gleaned from the sections, figs. 4b,c,d. The first (fig. 4) ex- 
hibits the termination of a young branch, and consists almost wholly of abdo- 
minal cavities with thin parietes ; the second (fig. 4c) gives the composition of a 
mature branch, not far from the middle and nearly equivalent in position to the 
preceding young case, and it exhibits numerous partially exposed large tubes 
with greater intervals, due partly at least to the section passing through side 
walls ; but a few small tubuli also are interspersed ; and the figure (fig. 4 d) repre- 
